class Base {
    keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
    utf8_encode (string) {
        const str = string.replace(/\r\n/g,"\n");
        let utftext = ""
        for (let n = 0; n < str.length; n++) {
            const c = str.charCodeAt(n)
            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }
        }
        return utftext
    }
    utf8_decode (utftext) {
        let string = "";
        let i = 0;
        let c = 0;
        let c3 = 0;
        let c2 = 0;
        while (i < utftext.length) {
            c = utftext.charCodeAt(i)
            if (c < 128) {
                string += String.fromCharCode(c)
                i++
            } else if ((c > 191) && (c < 224) ) {
                c2 = utftext.charCodeAt(i+1)
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63))
                i += 2
            } else {
                c2 = utftext.charCodeAt(i+1);
                c3 = utftext.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }
        }
        return string
    }
    // 加密
    encode (input) {
        let output = ""
        let chr1, chr2, chr3, enc1, enc2, enc3, enc4
        let i = 0
        input = this.utf8_encode(input);
        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output = output + this.keyStr.charAt(enc1) + this.keyStr.charAt(enc2) + this.keyStr.charAt(enc3) + this.keyStr.charAt(enc4)
        }
        return output
    }
    // 解密
    decode (input) {
        let output = ""
        let chr1, chr2, chr3, enc1, enc2, enc3, enc4
        let i = 0
        const inp = input.replace(/[^A-Za-z0-9+/=]/g, "")
        while ( i < inp.length) {
            enc1 = this.keyStr.indexOf(inp.charAt(i++));
            enc2 = this.keyStr.indexOf(inp.charAt(i++));
            enc3 = this.keyStr.indexOf(inp.charAt(i++));
            enc4 = this.keyStr.indexOf(inp.charAt(i++));
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 !== 64) {
                output = output + String.fromCharCode(chr2)
            }
            if (enc4 !== 64) {
                output = output + String.fromCharCode(chr3)
            }
        }
        return this.utf8_decode(output)
    }
    // 订单加密
    encodeNumber (input) {
        const str = this.encode(input)
        let num;
        for (let i = 0; i < str.length; i++) {
            if (str.charCodeAt(i) !== undefined || str.charCodeAt(i) !== null ) {
                num += str.charCodeAt(i) + "-"
            }

        }
        num = num.slice(0, -1)
        return num.replace("undefined", "")
    }
    //订单解密
    decodeNumber (input) {
        const arrList = input.toString().split("-").filter(item => item)
        let str;
        for (let i = 0; i < arrList.length; i++) {
            str += String.fromCharCode(arrList[i])
        }
        return this.decode(str.replace("undefined", ""))
    }
}

const base = new Base()

module.exports = Base